National Institutes of Health researchers already knew that the drug, called LY686017 neutralizes the action of a protein called NK1R (neurokinin-1 receptor), which is involved in the stress response in the brain.
The first hint that the drug might be useful in cutting alcohol cravings surfaced when the investigators noticed that mice who didn't have NK1R seemed to have less desire to consume alcohol.
To test their qualms, the researchers gave the NK1R-blocking drug to 25 recovering alcoholics, while giving 25 others an ineffective placebo treatment.
The analysis revealed that those who received the drug reported about 50 percent fewer alcohol cravings.
In the study, the alcoholics who were given LY686017 reported fewer spontaneous cravings for alcohol than did those who received the placebo. But the patients were kept in a hospital, away from the behavioural triggers such as social stress that are present in the outside world.
"They may get into a fight with their spouse or at work, and after that they may abstain for some period of time, but then they go past the bar where they used to drink. We wanted to mimic that in the lab," Nature quoted Heilig, as saying.
In order to create a stressful situation, the research team led the patients into a room and told them that they had to give a five-minute improvized talk to a committee of people in white coats, as if they were interviewing for their dream job.
"No one made it beyond 1.5 minutes. Everyone dried up after that. We had stern-looking people on the committee say 'Your time is not yet up'," Heilig said.
Patients were then allowed to smell alcohol.
Patients who had received LY686017 produced less of the stress hormone cortisol in response to this challenge did than those on placebo.
"This might be an approach that could be used for people who drink to relieve stress in their lives, or have anxiety disorders," said Raymond Anton, director of the Centre for Drug & Alcohol Programs at the Medical University of South Carolina in Charleston.